Apparatus, system and method for detecting defects of metallic lids

An apparatus for detecting defects of an element to be subjected to examination, comprising:

• lighting means for lighting the element, wherein said lighting means emits radiation beams according to two or more frequencies included within a set range and comprises a plurality of LEDs for emission of said radiation beams, such that an image acquisition unit for acquisition of images, is capable of detecting an image of said element lit by said lighting means, and
• a unit for processing images acquired by said image acquisition unit, suitable to detect said defects, wherein:
• each one of said radiation beams lighting said element according to an optical path, individuates an incidence angle (α) with respect to the surface of said element, the incidence angle (α) comprised between a grazing minimum incidence angle and a scattering maximum incidence angle, said lighting means being provided so that the incidence angle (α) realized by the optical path of each one of said radiation beams emitted by said lighting means is directly proportional or inversely proportional to a relevant emission frequency,
• said lighting means comprises a diffuser, having a substantially hemispherical shape, with a concavity faced downward and provided with a hole at the top of the diffuser, through which said image acquisition unit detects the image of said element;
• said LED of said lighting means are grouped in a first, second and a third LED assembly, said first LED assembly being installed according to a ring arrangement outside of said diffuser, so as to grazingly lighten said element, and being suitable to emit at a first minimum frequency (f1), said second LED assembly being installed according to a ring arrangement outside said diffuser, so as to light said element to be subjected to grazing scattering examination, and being suitable to emit at a second intermediate frequency (f2), and said third LED assembly comprising a first LED sub-assembly, installed according to a ring arrangement above said diffuser, and a second LED sub-assembly, arranged vertically above said diffuser, so as to light said element, and being suitable to emit at a third intermediate frequency (f3), and
• said lighting means further comprises a beam splitter mirror, provided above said diffuser reflecting the radiation beam emitted by said second LED sub-assembly on said element to allow detection of the image of said element by said image acquisition unit.